The invention relates to an injection molding machine with a stack mold for producing injection-molded parts, comprising a fixed exterior molding part, a central block supported in a rotational or swiveled fashion, as well as a movable exterior molding part, with molding cavities being formed between the molding areas at the interior sides of the exterior molding parts and the molding areas at opposite exterior sides of the central block.
Such stack molds are known in numerous embodiments, in order for example to produce twice the number of injection-molded parts on a single injection molding machine. In a further development of these stack molds, the central block is pivotal such that a two-component injection-molded part can be produced on a single injection molding machine, by first injection-molding a pre-mold in one level, then the central block or a part thereof being rotated with the pre-mold into a different level, and there the injection-molding process being finished. Such alternating tools are known, for example from DE 101 21 691 A1. Additionally, injection molding machines are known having a dual alternating tool, for example from WO 2005/077637 A1 or U.S. Pat. No. 7,081,222 B2, in which two partial pre-molds are produced on two central blocks arranged side-by-side, which then, after the rotation of the central blocks, are made to face each other and are interconnected by the closing motion of the stack mold.
In these injection molding machines of prior art it is problematic, however, that they are expensive in their construction due to the two rotary drives for the two central blocks and the necessary media guides as well as the devices for a linear displacement of the two central blocks in reference to each other. Additionally, such an injection molding devices is of great construction height and, in its open state, the turning circles of both central blocks have to be considered. Furthermore, such injection molding devices are only suitable for injection-molded parts that shall be interconnected positioned inside the molding cavities, for example for hemispheres being partial pre-molds, which shall be assembled to form a closed sphere.
A device having two external platens and a central rotary mold carrier element is known from DE 10 2006 024 481 A1, each comprising molding halves, which in a closed state form molding cavities for different molded parts. At the exterior platens, one displacement table is respectively provided having at least two molding halves each. By a longitudinal displacement, one of the molding halves of a displacement table can each be brought into the corresponding area of the molding half of the central mold carrier element. This way, two molded parts can be injection-molded simultaneously, while the respectively free molding halves of the displacement tables are being cleaned or coated with mold release agents. This way a rapid processing speed can be achieved. The production of multi-component injection molded parts is not provided in the device according to DE 10 2006 024 481 A1, though.
WO 2004/103676 A2 shows and describes a method and a device in which a rotary molding half is arranged between two exterior molding halves. The first exterior molding half as well as the rotary molding half each comprise molding cavities for two parts. In a first processing step, in the area of the first molding half, first and second injection-molded parts are formed, which after the rotation of the rotary molded half are connected to each other by one of the injection-molded parts being removed and being attached to the injection-molded part remaining at the rotary molded part. After another rotation of the rotary molding part, injection gating is attached to the injection-molded part assembled in that manner. For this purpose, the second exterior molding part comprises an appropriate molding cavity.
Using such a device injection-molded parts can be produced comprising three components. However, the device is very complicated and thus expensive, because at the lateral surfaces molding cavities are provided each for the first and the second injection-molded part.